Tuesday, August 16, 2016

Best infusion to date

I'm still on the learning curve regarding resin infusions, but every time I get to do one I learn something new and try something different.

In this latest example, I was building the Lower Folding Strut Beam Anchor Base Plate.


I spent one evening getting the fabrics prepared and everything laid up correctly.
I then applied the Vacuum Bag and pulled down the pressure. One small leak near a pleat was quickly isolated and fixed and then I turned the pump off and let it sit overnight since it was too late to mess with resin, but I did take the time to run the resin amount calculations:

34" * 16" = 544 sqin x 8 layers (of 18oz) = 4352 total fabric area
4352 *.31grams of epoxy per square inch = 1350 grams of mixed resin

1350/1.30 = 1038g PartA
     (1.30 is the 100:30 mix ratio)
1038 * .30 = 311g Part B

(This is an approximate amount required to fill the fabric itself, plus the feed lines and the amount left over in the consumables with some left in the bucket to ensure no air is pulled in near the end)

Note: I ended up with about 120 grams of mixed resin left in the bucket.

The next day after work I found that I still had a very good seal and had only lost 15 millibars over a 24 hour period.

I mixed up the resin and fed it into the stack via the small 1/4" (6mm) line to throttle the flow.
The wet out was really good and even.
Total infusion time was right at 40 minutes.

Once the resin had soaked into just over half of the Enka Fusion on the vacuum side, I clamped off the inlet and outlet tubes leaving the tube connected to the VacMobile (turned off) to keep a vacuum on the line itself.
What I was wanting to test/validate this time around was the "self leveling" characteristics of the excess resin. Since the inlet side of the infusion will always be a little heavier and thicker I was hoping to see that excess material flow into and fill up the Enka Fusion.

In this case, it worked perfectly as expected!

Infusion nearing completion.

If you look closely, you can see the difference in shading near the left side of the stack.
The darker green area to the right is where the stack is fully saturated, while the lighter green areas on the left edge are still pulling resin in.
Also notice that I moved the Enka channel on the right side about an inch (25mm) over the fabric stack, this is not a problem since I've found that the resin will move in all directions (to an extent) seeking to fill the voids.

When I first started practicing infusion, I was under the impression that the resin would only move toward vacuum and would never move in the opposite direction.

Some part notes


Scraps of foam are used to create an inlet pad.
I use a Dremel tool to bore a hole through the middle and then I cut a flow channel underneath the part while a quick pass on the sander rounds off the edges.
Puncturing the vacuum bag for the resin inlet is the last thing I do before introducing the resin.
Doing it this way eliminates a potential leak source.

Vacuum consumables removed - Nice looking part!


And a close-up shot

1 comment:

  1. Very exciting to see the infusion working as planned! Is this last close up the result of peel ply or just plastic on top? I'm curious about the shiny surface at the bottoms of the pattern divots.

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